Weel bearing assembly

ABSTRACT

A wheel bearing assembly is provided which needs no mounting of a brake rotor and which is small in the number of parts. By integrally forming a disk rotor for a brake on a wheel-mounting flange of an inner member, and providing raceways opposite double-row raceways of the outer member on separate inner ring members pressed onto a tubular portion of the inner member, it is possible to make it unnecessary to mount a brake rotor to the wheel bearing assembly, reduce the number of parts, and use different materials for the inner member and the inner ring members i.e. an FC-family cast iron, which is superior in seizure resistance, for the inner member, and a tough bearing steel for the inner ring member to achieve both excellent brake function and bearing function.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a wheel bearing assembly with anautomotive brake rotor.

[0002] Among automotive wheel bearing assemblies, there are ones fordriving wheels and non-driving wheels. FIG. 7 shows a conventional wheelbearing assembly for a driving wheel. It comprises an outer member 63provided with double-row raceways 61 and 62 on its inner periphery, aninner member 66 provided with double-row raceways 64 and 65 opposite theraceways 61 and 62 of the outer member 63, and double-row rollingelements 67 and 68 disposed between these opposed raceways 61, 64 and62, 65.

[0003] A tubular portion 69 to be mounted to an axle side is provided atthe inner periphery of the inner member 66, while a flange 70 to whichis mounted a wheel is provided at its outer peripheral side. Also, onthe outer member 63, a flange 71 to be mounted to a vehicle body side isprovided. Of two raceways 64 and 65 of the inner member 66, the raceway64 on the outer side with respect to the center of the vehicle body isformed directly on the outer periphery of the tubular portion 69, whilethe raceway 65 on the side near to the center of the vehicle body isformed on a separate inner ring member 72.

[0004] To the wheel-mounting flange 70, at an automobile manufacturer, adisk rotor 73 for a brake, which is a separate part, is adapted to bemounted by bolts 74, and further, a wheel is adapted to be mounted bybolts 75. As a material for the disk rotor 73, an FC-family cast iron,which is superior in seizure resistance, is ordinarily used. In the caseof a drum brake type, which is often used for a non-driving wheel, adrum as a brake rotor is mounted to the flange 70.

[0005] As described above, with a conventional wheel bearing assembly,since it is necessary to mount a brake rotor, which is a separate part,to the wheel-mounting flange of the inner member, a great deal oftrouble is needed at a customer's place for such mounting and runoutadjustment, and the number of parts is large.

[0006] Any runout of the brake rotor can cause vibrations or squealduring braking, or uneven wear of the brake rotor itself or the brakepad, thus worsening the vibration or squeal. Heretofore, automobilemanufacturers to whom the wheel bearing assemblies are supplied havecarried out the runout adjustment of the brake rotor. But such anadjustment is very troublesome and inefficient.

[0007] An object of this invention is therefore to provide a wheelbearing assembly which needs neither mounting nor runout adjustment of abrake rotor and which is small in the number of parts.

SUMMARY OF THE INVENTION

[0008] According to this invention, there is provided a wheel bearingassembly comprising an outer member to be mounted to a vehicle body andformed with double-row raceways on the inner periphery thereof, an innermember having at its inner peripheral end a tubular portion to bemounted to an axle side, and formed with double-row raceways opposite tothe respective raceways of the outer member, and double-row rollingelements arranged between the respective opposing raceways of the outermember and the inner member, the inner member having a wheel-mountingflange, characterized in that a brake rotor is integrally formed on thewheel-mounting flange.

[0009] By integrally forming the brake rotor on the wheel-mountingflange, it is possible to make it unnecessary to mount it and adjustrunout, and eliminate the parts for mounting the brake rotor.

[0010] By forming the portion where the double-row raceways of the innermember are to be formed on one or two separate inner ring members, it ispossible to use different materials for the inner member, which isformed integrally with a brake rotor, and the inner ring members. Byusing an FC-family cast iron, which is superior in seizure resistance,for the inner member and a tough bearing steel for the inner ringmembers, it is possible to let excellent brake function and bearingfunction coexist with each other, reduce the amount of an expensivebearing steel used and reduce the material cost.

[0011] The separate inner ring member may be divided into a first innerring member and a second inner ring member, and among the double-rowraceways, the outer raceway with respect to the center of the vehiclebody may be provided on the outer peripheral surface of the first innerring member and the inner raceway with respect to the center of thevehicle body is provided on the outer peripheral surface of the secondinner ring member. The first inner ring member is pressed onto the outerperipheral surface of the tubular portion of the inner member, and thesecond inner ring member may be a constant-velocity joint or a spindlemounted to the tubular portion. With this arrangement it is possible tosupply a constant-velocity joint or a spindle, which is a part to becoupled with an axle, to a customer, mounted beforehand on the wheelbearing assembly.

[0012] By forming the inner row of raceway of the second inner ringmember on a separate inner ring member, it is possible to make only theseparate inner ring member of an expensive bearing steel, ensure anexcellent bearing function and reduce the material cost.

[0013] By mounting the second inner ring member to the tubular portionof the inner member by caulking, it is possible to reduce the weightcompared with the conventional nut-tightening. Also, it is possible tomore rigidly fix a constant-velocity joint or a spindle to the tubularportion of the inner member and to stably retain the raceways formed ontheir outer peripheral surfaces.

[0014] By integrally forming the vehicle body-mounting flange on theouter member, it is possible to supply it to a customer with a knuckle,which is a part to be coupled with the vehicle body, mounted beforehandon the wheel bearing assembly.

[0015] By restricting the maximum variation of runout of the brakingsurface of the brake rotor within a predetermined value, it is possibleto suppress any runout of the braking surface of the brake rotor duringrotation. Also, troublesome runout adjustment at an automobilemanufacturer can be eliminated. Thus it is possible to avoid theproduction of vibration or squeak at braking and prevent uneven wear ofthe brake rotor itself and the brake pad.

[0016] The maximum variation of runout of the braking surface of thebrake rotor should be 100 μm. If it is 50 μm, the effect will beincreased.

[0017] Other features and objects of the present invention will becomeapparent from the following description made with reference to theaccompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIGS. 1-5 are vertical sectional views showing wheel bearingassemblies of first to fifth embodiments;

[0019]FIG. 6 is a vertical sectional view showing how the runout of thebraking surface of the brake rotor shown in FIG. 1 is measured; and

[0020]FIG. 7 is a vertical sectional view of a conventional wheelbearing assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0021] Embodiments of this invention is described based on FIGS. 1-5.FIG. 1 shows a first embodiment. This wheel bearing assembly is for adriving wheel, and comprises an outer member 4 formed with a flange 1for mounting to a vehicle body at the outer peripheral side, and withdouble-row raceways 2, 3 on its inner periphery, an inner member 9formed with a wheel-mounting flange 6 integral with a brake disk rotor 5on its outer peripheral side, and with a tubular portion 8 at its innerperipheral end to which is mounted a constant-velocity joint 7 at theaxle end, two inner ring members 12 and 13 having raceways 10 and 11opposing the raceways 2 and 3 of the outer member 4, respectively, andpressed onto the outer peripheral surface of the tubular portion 8, anddouble-row rolling elements 14 and 15 disposed between these opposedraceways 2, 10 and 3, 11, respectively.

[0022] The inner member 9 is made of an FC-family cast iron, while theouter member 4 and the inner ring members 12, 13 are made of a bearingsteel. Also, at both ends of the bearing portion where the rollingelements 14, 15 are disposed, seal members 16 are fitted.

[0023] The constant-velocity joint 7 is fitted in a spline hole 17formed in the tubular portion 8 of the inner member 9 and fixed by a nut18. The wheel is mounted by bolts 20 fitted in holes 19 formed in theflange 6. Also, in a bolt hole 21 provided in the flange 1 of the outermember 4, a knuckle 22 for connecting to the vehicle body is mounted bybolts 23.

[0024]FIG. 2 shows a second embodiment. This wheel bearing assembly isalso for a driving wheel. A constant-velocity joint 7 a fitted in aspline hole 17 a of a tubular portion 8 a is fixed by caulking. Thetubular portion 8 a of the inner member 9 a is formed slightly shorterthan in the first embodiment. The raceway 11 a on the side near to thecenter of the vehicle body is directly provided on the outer peripheralsurface of the constant-velocity joint 7 a. Other portions are the sameas in the first embodiment and are indicated by the same symbols as usedin FIG. 1.

[0025]FIG. 3 shows a third embodiment. This wheel bearing assembly isalso for a driving wheel. The raceway 11 b on the side near to thecenter of the vehicle body is provided on a separate inner ring member13 b pressed onto the outer peripheral surface of the constant-velocityjoint 7 b. Other portions are the same as in the second embodiment andare indicated by the same symbols as used in FIG. 2.

[0026]FIG. 4 shows a fourth embodiment. This wheel bearing assembly isfor a non-driving wheel and comprises an outer member 34 formed with aflange 31 for mounting to a vehicle body on the outer peripheral side,and with double-row raceways 32, 33 on its inner periphery, an innermember 39 formed with a wheel-mounting flange 36 integral with a brakedrum 35 on its outer peripheral side, and provided with a tubularportion 38 at its inner peripheral end to which is mounted a spindle 37at the axle end, two inner ring members 42 and 43 having raceways 40 and41 opposing the raceways 32 and 33 of the outer member 34, respectively,and pressed onto the outer peripheral surface of the tubular portion 38of the inner member 39, and double-row rolling elements 44 and 45disposed between these opposed raceways 32, 40 and 33, 41, respectively.

[0027] The inner member 39 is made of an FC-family cast iron, while theouter member 34 and the inner ring members 42, 43 are made of a bearingsteel. At both ends of the bearing portion where the rolling elements44, 45 are disposed, seal members 46 are fitted.

[0028] The spindle 37 is fitted in a spline hole 47 provided in thetubular portion 38 of the inner member 39 and fixed by a nut 48. Thewheel is mounted by bolts 50 fitted in a hole 49 provided in the flange36. Also, in a bolt hole 51 provided in the flange 31 of the outermember 34, a knuckle 52 for connecting the vehicle body is mounted bybolts 53.

[0029]FIG. 5 shows a fifth embodiment. This wheel bearing assembly isalso for a non-driving wheel. A spindle 37 a fitted in a spline hole 47a of a tubular portion 38 a is fixed by caulking. The tubular portion 38a of the inner member 39 a is formed slightly shorter. An inner ringmember 43 a formed with a raceway 41 on the side near to the center ofthe vehicle body is pressed onto the outer peripheral surface of thespindle 37 a. Other portions are the same as in the fourth embodimentand are indicated by the same symbols as used in FIG. 4. The raceway 41a may be directly formed on the outer peripheral surface of the spindle37 a.

[0030]FIG. 6 shows how the runout of the braking surface of the brakerotor 5 was measured. The wheel bearing assembly was mounted with theouter member 4 fixed to a bench 24 so that the inner member 9 berotatable. In this state, the inner member 9 was turned 360° and therunout of the braking surface of the brake rotor 5 was measured by adial gauge 25. Since its runout is greater at the radially outerportion, the runout was measured with the dial gauge 25 abutting thebraking surface of the brake rotor 5 at the radially outer portion formore strict runout control.

[0031] The maximum variation of runout of the braking surface of thebrake rotor should be 100 μm. If it is 50 μm, the effect will beincreased.

[0032] As described above, with the wheel bearing assembly of thisinvention, since a brake rotor is integrally formed on the wheelmounting flange of the inner member for mounting a wheel, the mountingof a brake rotor and run-out adjustment are eliminated and it ispossible to reduce the number of parts.

[0033] Also, by forming the portion where the double-row raceways of theinner member are to be formed on one or two separate inner ring members,it is possible to use different materials for the inner member body,which is formed integrally with a brake rotor, and inner ring members.By using an FC-family cast iron, which is superior in seizureresistance, for the inner member and a tough bearing steel for the innerring members, it is possible to achieve both excellent brake functionand bearing function, reduce the amount of use of an expensive bearingsteel and reduce the material cost.

[0034] Further, by dividing the inner ring member into a first innerring member and a second inner ring member, utilizing theconstant-velocity joint or spindle mounted to the tubular portion of theinner member as the second inner ring member, and providing the racewayon the side near to the center of the vehicle body on its outerperipheral surface, it is possible to supply it to a customer with aconstant-velocity joint or a spindle, which is a connecting part withthe axle, mounted beforehand on the wheel bearing assembly.

[0035] Also, by forming the portion on which the inner raceway of thesecond inner ring member is to be provided on a separate inner ringmember, it is possible to ensure an excellent bearing function andreduce the material cost.

[0036] By using caulking for the mounting on the tubular portion of thesecond inner ring member, it is possible to reduce the weight comparedwith the conventional nut-tightening method. Also, it is possible tomore rigidly fix a constant-velocity joint or a spindle to the tubularportion of the inner member and to stably retain the raceways formed onthe outer peripheral surfaces.

[0037] By integrally forming the vehicle body-mounting flange on theouter member, it is possible to supply it to a customer with a knuckle,which is a connecting part with the vehicle body, mounted beforehand onthe wheel bearing assembly.

[0038] By restricting the maximum variation of runout of the brakingsurface of the brake rotor within a predetermined value, it is possibleto suppress any runout of the braking surface of the brake rotor duringrotation. Also, troublesome runout adjustment at an automobilemanufacturer can be eliminated. Thus it is possible to avoid theproduction of vibration or squeak at braking and prevent uneven wear ofthe brake rotor itself and the brake pad.

What is claimed is:
 1. A wheel bearing assembly comprising an outermember to be mounted to a vehicle body and formed with double-rowraceways on the inner periphery thereof, an inner member having at itsinner peripheral end a tubular portion to be mounted to an axle side,and formed with double-row raceways opposite to the respective racewaysof said outer member, and double-row rolling elements arranged betweenthe respective opposing raceways of said outer member and said innermember, said inner member having a wheel-mounting flange, characterizedin that a brake rotor is integrally formed on said wheel-mountingflange.
 2. The wheel bearing assembly as claimed in claim 1 wherein saiddouble-row raceways of said inner member are formed on one or twoseparate inner ring members.
 3. The wheel bearing assembly as claimed inclaim 2 wherein said separate inner ring member is divided into a firstinner ring member and a second inner ring member, wherein among saiddouble-row raceways, the outer raceway with respect to the center of thevehicle body is provided on the outer peripheral surface of said firstinner ring member and the inner raceway with respect to the center ofthe vehicle body is provided on the outer peripheral surface of saidsecond inner ring member, and wherein said first inner ring member ispressed onto the outer peripheral surface of said tubular portion ofsaid inner member, and said second inner ring member is aconstant-velocity joint or a spindle mounted to said tubular portion. 4.The wheel bearing assembly as claimed in claim 3 wherein the portion onwhich said inner-row raceway of said second inner ring member isprovided is formed on a separate inner ring member.
 5. The wheel bearingassembly as claimed in claim 3 or 4 wherein said second inner ringmember is mounted to said tubular portion of said inner member bycaulking.
 6. The wheel bearing assembly as claimed in any of claims 1-5wherein a flange for mounting a vehicle body is integrally formed onsaid outer member.
 7. The wheel bearing assembly as claimed in any ofclaims 1-6 wherein the maximum variation of runout of the brakingsurface of said brake rotor is restricted within a predetermined value.8. The wheel bearing assembly as claimed in claim 7 wherein saidpredetermined value is 100 μm, preferably 50 μm.